The increasing demand for spectacle-free refractive correction has generated interest in the use of phakic IOLs for refractive correction of high myopia. While LASIK has been highly successful for hyperopia and myopia up to approximately 10 D, the correction of larger refractive errors has had limited success because of the need to ablate excessive corneal tissue. The challenge of today's phakic IOLs remains to deliver precise, accurate and permanent correction of spherical and astigmatic refractive error. The objective of this program is to develop a soft acrylic light adjustable phakic intraocular lens (LAL) for the treatment of high myopia and high myopia with astigmatism. The phakic LAL is an IOL whose power can be precisely adjusted with light 2-4 weeks after implantation to correct any refractive errors due to incorrect power calculations, the surgical procedure and wound healing to insure the patient is spectacle free after surgery. The soft acrylic material is chosen because of its high refractive index to reduce lens thickness and thereby minimize the incidence of endothelial or iris cell loss, and cataract formation of the healthy natural lens by reducing the risk of contact of the implanted phakic lens with these cells. The primary goal in Phase I is to select the acrylic material for phakic IOLs for high myopia and myopia with astigmatism and demonstrate the power change through shape or refractive index change or both. In order to achieve the goal, six aims are proposed: (1) Develop a soft acrylic LAL composition based on initial exploratory work, (2) Characterize the test formulations for optical clarity and refractive index, (3) Evaluate the photoreactivity of the macromer in cured test formulations by Differential Photocalori-metry (DPC), (4) Determine the level of available unreacted monomer remaining after crosslinking of the matrix by thermal initiation using GC and GPC analyses of solvent extractables, (5) Fabricate test lenses from test formulations and evaluate for power adjustment by interferometric measurement to identify range of feasible power change, and (6) Select the candidate material for Phase II development based upon the test data generated in Phase I.